It doesn't need to, assuming you're using something like rclone [1], where the encryption is done on the "client," which in this case would be the GP's home server. The client does the encryption, treating the disk attached to the Raspberry Pi as an untrusted third-party disk. As long as you keep the decryption key safe (e.g., on a USB stick stored off-site), you should be good to go in the event that you need to pull data and decrypt it.

[1] https://rclone.org/